Tips for growing and pruning roses in a hot dry desert climate

Tips for growing roses in a hot, dry garden

Austin rose Lilian Austin — The fragrant David Austin rose, ‘Lilian Austin’, will bloom again and again throughout the summer.

We love roses. We grow them. We cut them for bouquets in our home. We spray aphids off their leaves in the mornings. We fertilize them (irregularly) and cut the shrubs back in winter. We are, however, not rose experts by any measure.

What a professional rose grower recommends

But recently we attended a lecture by Luke Stimson of David Austin Roses and learned — much to our surprise — that all David Austin Roses sold in the United States are grown in Arizona where the temperature reaches 90F on a daily basis for months on end. This makes these highly fragrant roses ideal for hot weather gardens.

Austin 'The Squire' rose deep red crimson — The Squire rose by Austin Roses.

If you are not familiar with David Austin Roses, a little background: David Austin, who passed away recently after living into his 90s, began developing highly fragrant roses, many with the flower shape of a peony, decades ago in England near the wet and rainy Welsh border. Some people simply call them “English roses”. They are the most popular roses in the world.

In recent years Austin scientists have expanded their research into creating disease-resistant roses and roses for warmer, dryer climates.

The highly fragrant ‘Sir Edward Elgar’ rose lives side by side with a big-leafed, 5 foot tall Cardoon (Cynara Cardunculus) as part of a flower border.

Stimson advocated our favorite practice: plant roses as part of a traditional border–not as single, isolated specimen plants, neatly separated and labeled, as we often see in public rose gardens.

One benefit of planting roses in a perennial border is that the rose roots are more likely to be shaded most of the day and the rose leaves offer shade to other companion plants beside them in the border. Plants with cool roots grow better in the desert. (Except palms.) Roses should be planted where they will receive at least 6 hours of sun per day.

Smelly food

He also revealed what fertilizer Austin roses receive in Arizona: AGED horse manure–18 inches of it! He emphasized the “aged’ factor–fresh manure will burn the plants in a flash. If you have a source for manure, be sure to let it sit at least 5 to 6 months before you use it.

Alternatively, you can ask your local garden center or nursery for organic mulch which combines aged manure with other components. This should not be as smelly as pure aged manure. You may also prefer an entirely different and less odoriferous solution: organic rose food you can pour from a bag. Commercial rose food, however, will not do much to balance the pH of the soil, so if you use it be sure to add a lot of organic compost to your flower bed.

About watering roses

Alas, roses like water and they should not be planted as part of a xeriscape border that is irrigated only once a week. And they need soil that drains well. Both these factors can create difficulties for hot climate gardeners.

Many areas in the Southwest have hard-as-rock clay soil so we recommend that you dig a hole at least twice as wide than the root ball to give the roots space to grow. You may also want to dig the hole much deeper than the root ball and backfill it firmly to the correct level. (If the hole is small, you are effectively planting your rose in an in-ground terra cotta pot with no drainage holes)

Morning watering will help prevent diseases such as black spot. If you can only water in the evening, water at the roots; avoid splashing water on the leaves if at all possible. Standing water on the leaves is a major source of rose diseases.

Pruning roses – Yes or No?

Stimson also suggested a simple, practical annual pruning technique that conforms to what we have always done in our garden. In November or December, he said, cut your roses back to knee height — if you want a taller shrub, cut the roses back to waist height. For a shorter shrub, shape the plant during summer as you clip of the dead rose blooms. Be sure to cut out any stems that cross so when the roses regrow in Spring the new growth and leaves will not prevent air circulation in the center of the plant — although air circulation in a hot dry climate is not usually an issue!

At this point rose experts will probably be claiming that each stem should be cut back by 5 buds. Personally, we like the simple knee height measurement better. Space allowing, the Austin catalog advocates not pruning annually at all.